Should You Run Two-a-Days?

"Doubles" have their place in training, but use them wisely

Running more than once per day sounds like serious training. Many elite runners incorporate "doubles" in some way, and this training pattern offers a number of benefits. Most runners, however, should resist the urge to shift from single runs to doubles as they increase training mileage, and instead add miles to single runs. Let's look at when double workouts are and are not beneficial, and how to add them to your training program.

A guiding principle

Do not do double workouts until you have maximized the training volume you can handle in single daily workouts. The main reason for this is that staying with longer single runs builds endurance. The weekly mileage at which you should incorporate doubles is outlined in the table below. The longer your target race, the more your training should focus on endurance-based adaptations such as depleting your glycogen reserves to provide a stimulus to store more glycogen, and training your muscles to utilize more fat at a given speed. You will better stimulate these adaptations with, say, a single 12-mile run than a seven-mile morning run and a five-mile evening jaunt at the same pace.

The shorter your goal race, the lower the mileage at which you should incorporate doubles. If you are preparing for a 5K, your interval workout is the most important training session of the week, and you will need to keep your legs fresh. You will also want to maintain a faster pace during some of your training runs, which is accomplished more easily during two short runs than one longer run.

If you are preparing for a marathon, do not do doubles unless you are running more than 75 miles per week. Up to that level your daily running, including long run and medium-long run, should be enough to get in the necessary miles.

When to add doubles

Race Distance

Weekly mileage exceeds

5K or shorter

55

8K to 12K

60

15K to 25K

70

30K to marathon

75

Always ask why

Like any other element of training, do doubles with a purpose. In order of priority, you should add doubles as easy second runs on days that include the following: 1. Interval training; 2. A tempo run; 3. A race of 10K or shorter; 4. Recovery running; 5. A medium-long d